Messi's renewal proved the most dramatic of the day's events, with some reports claiming he had signed the deal around lunchtime only for the player's camp to release a statement suggesting he could yet leave the Camp Nou before, finally, the club confirmed the new contract in the early evening.

Madrid-based newspaper AS reports that Messi had posed for the photo with club president Josep Maria Bartomeu at 2 p.m. local time but the final details of the deal were only agreed during a board meeting that commenced an hour later, with the Argentina forward finally putting pen to paper as he prepared to embark on a flight to South America for the World Cup after 6 p.m.

However, the statement from the Messi camp appeared to hint at a frustration with the whistles he received from some supporters at the Camp Nou during Saturday's 1-1 draw with Atletico Madrid, and Alba said his teammate deserves more respect.

The Spain international said: "It is easy to criticise and make comments, but they are very unjust. He has won the Ballon d'Or four times and for sure he will win more. If they criticise him, what will they say about me?"

Alba also said he could not imagine Messi leaving the club, adding: "I do not imagine a future for Barca without him."

However, a number of high-profile players will be leaving this summer, with Bartomeu having promised "deep changes" to the squad.

Alba, 25, said he trusts the president and the club's directors to make the right decisions this summer.

"He is in charge," he said. "He decides the club's movements, the good and the bad. If the president has said deep changes then he will have his reasons for that. For sure, whatever they do will go well for us. Players coming and going is part of the law of life."

Alba is also positive that former Barca star and Barca B coach Luis Enrique, who replaces Gerardo Martino after a year at Celta Vigo, will succeed.

"As a player I liked him a lot and as a coach people have told me very good things about him," he said. "As a player he was an example. His character stood out."